The invention relates to a surgical cutting instrument having a rotating cutter within a stationary outer tube. The outer tube has an open end adjacent to the cutter and one or more side openings having edges that cooperate with the rotating cutter to cut tissue. This type of cutter, when sized and constructed for insertion into a joint, is particularly useful for arthroscopic surgical procedures.
Surgical cutters constructed with an outer guide tube and an inner cutting member are known in the art. The tube and cutter are generally sized and constructed for specific surgical uses. Significant factors influencing the viability of a cutter include the type of tissue to be cut and the rate at which tissue is to be cut. The mechanism for cutting the specific tissue at the desired rate and consequently the design of the cutting structure embody the most significant differences among these cutters.
U.S. Pat. Nos. 3,618,611, 4,203,444, 4, 274,414, and 4,368,734 are representative of surgical cutters that are constructed with a stationary outer tube and a rotating inner tube. U.S. Pat. No. 3,618,611 discloses a cutter for delicate surgical removal of tissue which has tubes with adjacent openings in the sides of bullet shaped ends. The inner tube has multiple cutting points in the edge of the opening in the inner tube. As the inner tube is rotated, tissue is captured when the openings are aligned and sheared as the inner tube is rotated. U.S. Pat. Nos. 4,203,444 and 4,274,414 disclose concentric tube cutters constructed for arthroscopic surgery of joints. U.S. Pat. No. 4,368,734 discloses a cutter constructed for removal of relatively hard tissue of advanced cataracts.
U.S. Pat. Nos. 3,732,858, 3,945,375, 4,512,344, 4, 517,977, and 4,649,919 are representative of surgical cutters that are constructed with an outer tube and a solid cutter rotating within the outer tube. U.S. Pat. No. 3,732,858 and 3,945,375 disclose surgical cutters for removal of tissue from the eye. The cutters disclosed by these patents have an outer tube with a closed or partially open end and drill-like solid cutters. U.S. Pat. No. 4,512,344 discloses a surgical cutter for arthroscopic surgery having an outer tube with an open end and one or more side openings. The inner cutters have generally longitudinal cutting edges lying along the axis of the cutter and a cutting edge lying in an axial plane. U.S. Pat. No. 4,517,977 discloses a surgical cutter for removal of fibrous brain tissue. The outer tube has closed sides and a partially open end. The solid cutter has a cutting edge lying in a radial plane. U.S. Pat. No. 4,649,919 discloses a surgical cutter for arthroscopic joint surgery having an outer tube with an open end and two side openings extending from the end of the tube. The inner cutter is recessed from the end of the tube and has an auger-like cutter having a "fish-tailed" end profile. A cutting edge extends radially along each blade of the cutter providing two concave cutting edges. The radial extent of each blade may be provided with a short cutting edge. The outer tube has tabs that extend beyond the inner cutter and over a small portion of the radial extent of the inner cutter.
Surgical cutters known in the art may have general application, but are best suited to a particular surgical use. Tissue characteristics, the amount of tissue and rate of removal vary significantly among surgical uses. Aggressive cutting and removal of a significant amount of tough tissue, such as fibrous cartilage of the knee presents a difficult surgical use for which some cutters known in the art ar not ideally suited.